Engine systems include a variety of sensors for measuring ambient conditions, such as ambient temperature, pressure, humidity, etc. Based on the ambient conditions, one or more engine operating parameters may be adjusted to optimize engine performance. For example, based on ambient temperature (for example, the temperature of the air charge received in the engine), parameters such as combustion air-fuel ratio, spark timing, EGR, and purge control may be adjusted. As a vehicle starts-up after a prolonged period of engine inactivity, the sensors require a certain amount of time to initialize before they are fully functional and are able to measure ambient conditions accurately.
One example parameter used for engine control is air charge temperature (ACT) which is estimated via an intake air temperature (IAT) sensor located in an engine intake air passage. After a period of engine inactivity, on vehicle start-up, ACT estimation by the IAT sensor may not be immediately reliable as the sensor initializes during this period. To address this issue, immediately after vehicle start-up, a function of a preset/default value of ACT and/or a filtered reading of the IAT sensor may be used for engine control. However, the inventors have recognized that the ACT value estimated from the function may not be accurate since the preset value may not be close to the actual ambient temperature at that location and at that time. As such, it may take an amount of time (initialization or response time) for the IAT sensor to fully initialize before the ACT value output by the sensor may be directly used. In the meantime, the use of the inaccurate preset value can result in degraded engine performance. The problem may be exacerbated when the engine is restarted after a long period of vehicle inactivity since the longer the period of inactivity, the difference between the actual temperature value and the default temperature value in sensor software may be higher. The last measured temperature value at the vehicle may be significantly different from the current actual temperature. Once the sensor is fully initialized, it is able to estimate ambient conditions within a given error range of the true physical value.
In an alternate approach, shown by MacNeille et al. in US 20120158207, when an ambient weather sensor is limited in its capability, ambient weather conditions are retrieved from a remote server using global positioning system (GPS) coordinates. The weather conditions received from the remote server may be directly used for adjusting engine operations. However, the inventors have recognized potential issues with this approach also. Specifically, the actual engine conditions of the vehicle may be different from ambient conditions as received from the external server. As an example, if a vehicle is parked in a garage, the ambient temperature and humidity as received from the remote server may be significantly different from the actual temperature and humidity experienced at the engine of the vehicle. Herein, as with the use of the preset value, the use of an inaccurate ambient condition estimate can result in degraded engine performance.
As such, there may be one or more other vehicle sensors whose operation and control is affected by the accuracy of the estimated ambient condition. As an example, warming up of an exhaust gas oxygen sensor (such as a UEGO sensor) may be inferred based on the air charge temperature. During the phase where the UEGO sensor has not yet warmed up (such as when the estimated ACT is below a threshold temperature), engine air/fuel ratio may be controlled in an open loop mode. A transition to closed loop control of the engine air/fuel ratio is thus delayed until the UEGO is determined be warm enough, as inferred from the estimated ACT being higher than the threshold. As a result, delays in IAT sensor initialization, and inaccuracies in ACT estimation can result in delays in transitioning of air/fuel ratio control to the closed loop mode, resulting in a drop in fuel economy.
The inventors herein have identified an approach by which the issues described above may be at least partly addressed. One example method for adjusting engine parameters during sensor initialization comprises: during a vehicle start from rest, adjusting an engine actuator based on an ambient condition determined from remote of the vehicle while a vehicle sensor initializes, and then adjusting the engine actuator based on the ambient condition determined from the sensor. In this way, the ambient condition estimate used while a sensor initializes may be rendered more accurate.
As an example, in response to an engine start from rest following a longer period of vehicle inactivity, ambient conditions (e.g., ambient temperature, ambient humidity, etc.) may be obtained from remote of the vehicle while a vehicle sensor (e.g., intake air temperature sensor, humidity sensor, etc.) initializes. For example, the ambient conditions may be retrieved from an external server. The controller on-board the vehicle may include a navigation system via which a location (e.g., GPS co-ordinates of the vehicle) may be transmitted to the external server over a network. Accordingly local ambient conditions for that location may be retrieved from the external server. In another example, the on-board vehicle controller may be communicatively coupled to an indoor (e.g., garage, storage area) temperature sensor through wireless network. In yet another example, the on-board vehicle controller may be communicatively coupled to the on-board controller of one or more other vehicles, such as using vehicle to vehicle (V2V) communication technology. The one or more other vehicles may include other vehicles within a threshold radius of the given vehicle, other vehicles having the same make or model, other vehicles of a fleet to which the given vehicle belongs, etc. Following the vehicle start-up, ambient conditions may be retrieved from the one or more vehicles. For example, a statistical or weighted average of the values retrieved from the one or more vehicles may be used to estimate the ambient condition. In another example, the controller may use a weighted average of the estimate retrieved from the remote vehicles and the estimate retrieved from the remote server. Further still, the weighted average value may be used alongside a filtered reading of the vehicle sensor, or a filtered reading of a default sensor value, for achieving a better accuracy in estimation of engine operating conditions. The remote data is relied on while the sensor initializes. As such, if the vehicle is restarted after a shorter period of inactivity, instead of relying on the remote data, a default value of the ambient condition may be applied until the sensor initializes. Once the sensor has initialized, the sensor output may be used to determine the ambient conditions.
In this way, data regarding vehicle ambient conditions, such as temperature and humidity, may be obtained from one or more reliable sources external to the vehicle during sensor initialization. By relying on ambient condition data retrieved from an external server and/or a remote vehicle, a more accurate estimate of the ambient condition may be provided as compared to a preset value. The technical effect of using ambient condition data from external sources is that sensor initialization time may be significantly reduced. By reducing the initialization time for a vehicle sensor, such as an IAT sensor, accurate ambient condition estimates, such as ACT estimates, may be obtained within a shorter time, reducing a delay in transitioning of air/fuel ratio control from open loop to closed loop mode. Overall, engine performance and fuel economy is improved.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.